Generally speaking, difficulties in repairing manifolds arise from the inability to adequately secure manifolds in place, center and align manifolds during machining, and adapt manifold holding tools to accommodate resurfacing equipment from diverse manufacturers. Since xe2x80x9cVxe2x80x9d block designed engines were introduced to the general automotive consumer in the 1930""s and 40""s, dedicated tooling at the Original Equipment Manufacturer (OEM) level has been required to create precision intake and exhaust manifolds having very specific angle and size limitations. This specialized tooling has typically been unavailable to the average automotive rebuilder. Thus, manifolds having reparable damage in the form of corrosion, cracks, and warp are often discarded because remachining those manifolds to original specification is exceedingly difficult without manufacturer specific tooling. Even in circumstances where specialized tooling is available, the variety and type of manifolds generally encountered by the typical automotive rebuilder renders any type of specialized tooling of limited utility: modifying OEM tooling to accommodate various OEM manifolds is nearly impossible.
Because accurately machining a manifold is so difficult, many shops have adopted questionable practices to compensate for their inability to precisely machine damaged manifolds. For example, some shops cut the cylinder head""s manifold mounting face to compensate for material that should have more properly been removed from the manifold mounting face itself. This practice creates heads that are no longer standard and therefore not freely interchangeable within their customary applications. Other shops drill oversized intake manifold bolt holes so that the intake manifold appears to fit the engine block properly while in fact it does not. This practice often results in hidden problemsxe2x80x94e.g. port misalignment, vacuum leaks, and fluid leaks. Still other shops sell replacement manifolds rather than attempt difficult repairs that, given the proper tooling, would otherwise be cost effective to repair. Finally, some shops, attempting to overcome the lack of tooling, use abrasive belts to machine manifolds. Although manifolds machined with abrasive belts have the appearance of precision machining, the opposite is true because the machinist cannot retain adequate control over the machining process.
Finally a costly practice in the automotive repair industry is modifying manifolds for use with performance engines. Often performance shops create modified engine blocks and cylinder heads that cannot accommodate OEM manifolds. Machining manifolds to match custom blocks and heads requires a high degree of skill and precision causing a completed performance engine""s price to be substantially higher than conventional repair and machining.
These practices combine to cause more problems than they solve resulting in poorly machined manifolds and inadequately repaired engines.
The present invention is a universal manifold holding fixture for holding intake manifolds during machining processes comprising a length adjusting assembly that establishes and maintains a centerline with respect to the fixture and the intake manifold held by the fixture. The length adjustment assembly comprises a centering shaft for attachment with a machining tool, a pair of adjustable endplates in communication with the centering shaft and a pair of length adjusting plates for accommodating intake manifolds of varying lengths in the fixture.
The holding fixture further comprises a manifold attachment assembly comprising a centering slide block and a carburetor flange mounting plate. The centering block centers the intake manifold with the centering shaft. In one embodiment, the centering block is clamped to the centering shaft. In yet another embodiment, the centering block is milled from aluminum to avoid marring the centering shaft. The carburetor flange mounting plate serves to attach the intake manifold with the fixture. In one embodiment, the carburetor flange mounting plate is configured to receive a plurality of different manifolds. In another embodiment the plate is configured to receive a specific manifold.
The holding fixture further comprises a machining guide assembly. The purpose of the machining guide assembly is to align the intake manifold to the centerline established by the centering shaft. Once the intake manifold is aligned to the centering shaft, it is removed to allow machining of the intake manifold. In one embodiment, the machining guide assembly comprises a pair of side locating bars that are adjustable to different intake manifold specifications. In another embodiment, the machining guide assembly comprises a pair of bottom centering plates, which are aligned with a user defined center hole located on the intake manifold.
Finally, the holding fixture comprises a clamping assembly to provide tension across the manifold. The clamping assembly comprises a plurality of split ring clamping collars that may be adjusted along the centering shaft. The clamping rings further comprise collar-clamping bolts that exert isometric tension to the intake manifold. In one embodiment the collar-clamping bolts are stepped to accommodate varying intake manifold bolt holes.